Apparatus for carburizing



Patented Apr. 16, 1929.

UNITED STATES PATENT OFFICE.

PETER CHAMBERS, OF LOS ANGELES, CALIFORNIA, ASSSIGNOR TO SECURITY MANU- FACTURING COMPANY, 0]? LOS ANGELES, CALIFORNIA, A CORPORATION OF DELA- WARE.

APPARATUS FOR CARBURIZING.

Application filed November 3, 1925. Serial No. 66,535.

This invention relates to the art of carburization of steel.

A common method of carburizing steel consists in heating the articles to be carburized to a carburizing temperature and then introducing a carburizing gas into the chamber in which the articles are being heated to efl'ect cementation.

In an application entitled Process of carburizing steel, invented jointly by William H. Fisher and myself, and filed November 9, 1925, Serial No. 67,822, a novel process of carburizing steelis disclosed. This process involves the introduction of a liquid carburizing agent into a carburizing chamber without any substantial vaporization thereof before it enters the carburizing chamber. The carburized liquid passes into the carburizing chamber through a nozzle which is mounted at the end of a tube which extends from the carburizing chamber. The nozzle is located remotely from the carburizing chamber so that it will remain cool enough to prevent a vaporizing of the carburizing agent therein,

' and so that the drops of the carburizing liquid falling from the nozzle will gain enough velocity to carry them a distance into the carburizing chamber before vaporization thereof occurs. 7

It is an object of this invention to provide a method of carburization which consists in dropping a carburizing briquette into a carburizing chamber which is at a carburizing temperature, the carburizing briquette being reduced to gases and free carbon therein.

It is also an object of this invention to provide a carburizing apparatus having a carburizing chamber and means for dropping a carburizing briquette into the carburizing chamber.

It is a still further object of this invention to provide apparatus having a carburizing chamber, a briquette chamber arranged so that it will not heat sufficiently to cause vaporization of the carburizing briquette therein,

and means for introducing the carburizing briquette into the carburizing chamber.

It is a still further object of this invention to provide a carburizing briquette which consists of a pyroligneous substance, such as pine tar, and a vehicle therefor.

It is a still further object of this invention to provide a carburizing briquette which consists of a carburizing agent mixed with a vehicle in the form of pyroligneous particles, such as sawdust.

Other objects and advantages of this invention will be made manifest hereinafter.

Referring to the drawing in which I illustrate a preferred embodiment of my invention,

Fig. l is a sectioned elevational view of an apparatus of my invention.

Fig. 2 is a cross section taken on the line 22 of Fig. 1 and shows a means for introducing a carburizing briqu'ette into the carburizing chamber of my invention.

Fig. 3 is a perspective view briquette of my invention.

l/Vith reference to Fig. 1 the apparatus of my invention consists of a furnace 11 having side Walls 12, a floor l3 and atop 14. The side walls, floor and top of the furnace 11 have outer metallic Walls 17 and inner walls 18 which are made from a heat insulating mate- 20 to which pipes 21 connect, these pipes 21 ex- 20 to which pipes 21 connect, these pipes 21 extending through opposite side walls 12 of the furnace 11. he pipes 21 are connected to manifold pipes 22 by means of which gas is supplied to these pipes 21, this gas being introduced into and ignited in the chamber 20.

Extending into the heating chamber 20 through an opening 24 in the top l-l of the furnace 11 is a shell 25 which provides a carburizing chamber 26. The lower end of the shell 25 rests in a recess 27 formed in the floor 13. The upper end of the shell 25 is closed by a cover 29 having a channel 30 into which the upper edge of the shell 25 extends. The cover 29 is provided with openings 32 and with eyes or hooks 34. to facilitate the removing and placing of the cover 29.

The lower end of an extension or drop tube 37 is secured in an opening 38 of the cover 29 so that the interior of the tube 37 connects to the carburizing chamber 26. At the upper end of the tube 37 is a casting 40 which provides a briquette chamber 41. The lower part of the casting 40 is formed to accommodate a gate 43. The gate 43 rests in a recess 44 formed in a projecting portion 45 of the of a carburizing casting 40, and is adapted to move from the full line position of the drawings, into a brolren line position indicated at 46 in Fig. 2. When the gate 43 is in full line position, it closes the lowerend of the briquette chamber ll and when it is in open position or in that position indicated by dotted lines 46, it provides communication between the briquette chamber 41 and the upper end ot the drop tube 37. The gate 43 is moved between the two mentioned positions by means of a rod e8 which extends to the exterior of the casting 40 and has a handle 4-9 on the outer end thereof. The upper end of the briquettc chamber is closed by a cover 52.

A work table 55 is placed in the lower part of the'carburizing chamber 26 on which work tobe carburized may be placed. Extending through the fioor 13 of the furnace 11 and Vertically into the carburizing chamber 26 is a thermo-couple tube 57 in which a thermocouple element 58 is placed. This thermocoupleelement 58 is connected to a galvanometer 59 by wires 60. The thern'io-couple unit 58 is of standard construction and the galvanometer 59 is calibrated to indicate the temperature in the carburizing chamber 26 according to the flow of electricity therethrough, which flow of electricity is determined by the thermo-couplo unit 58.

A carburizing briquette of my invention is shown in Fig. 3. I prefer to make the carburizing briquette 65 from a carburizing agent in the form of a pyroligneous substance such as pine tar, which is a liquid, and a suitable vehicle which are mixed together and then pressed into briquette form, as shown in Fig. 3. As a vehicle I desire to use sawdust, which is itself a pyroligneous substance but is a solid. It is obvious that the shape of the briquet-te 65 is not important to the invention.

The operation of my invention is substantially as follows:

Gas is supplied to the heating chamber 20 ot the furnace 11 through the pipes 22 and 21. The gas is ignitedin this chamber 20 and the chamber 26 is thus heated to a proper carburizing ten'ipcrature, this temperature being. indicated on the galvanometer 59. When the proper temperature has been reached, the cover 29 isremoved from place and the articles to be carburized are placed in the chamber 26 on the table 55. The cover 29 is then replaced to close the upper end of the carburizing chamber 26. as shown in the drawings. The gate l?) is in the position shown in full lines in the drawing so that the lower part of the briquette chamber l1 is closed. The cover 52 of the chamber 41 is then swung into open position and a carburizing briquette 65 is placed in the chamber .41 resting on the upper face of the gate 43,

as shown, the cover being thereafter returned to closed position. At the proper time the gate 43 is removed from full line position into the position indicated by dotted lines 46 1n Fig. 2. The briquette 65 at this time is permitted to drop through the tube 37 into the carburizing chamber 26'.

It should be understood that the interior of the carburizing chamber 26 is at a carburizin temperature. which is very high. When the briquette drops into the carburizing chamber 26, it is instantly acted upon by the heat and v is quickly transformed into gas and free carbon. The solid and gaseous resultantsof the vaporization are thoroughly distributed upon and around the articles being carburized.

By providing a long drop tube 37' the briquette chamber i=1 may be located remotely from the carburizing chamber 26 and will therefore not be heatedto a temperature high enough to cause any vaporization of the carburizing agent of the briquette. This is one advantage of the long tube 37. Another advantage of the long tube is that it allows the carburizing briquette 65 to gain considerable velocity so that it will fall to thelower part of the carburizing chamber 26 before it is vaporized. This is effective in thoroughly distributing the free carbons and gases around and between the articles being carburized.

The use of the briquette forms an important part of my invention, this briquette being more economical and more convenient than a. carburizing liquid by. itself. The carburizing briquette may be readily handled and the equipment used is of such a character that there is nothing to clog up. The briquette may be fairly clean so that it will not stick to the walls of the briqu'ettechamber 41. Furthermore, the briquette has sufficient mass so it will gain considerable velocity in falling through the drop tube37, and it is therefore assured that it will drop to the lower part of the chamber 26 before it becomes vaporized. I prefer to use pine tar or other pyroligneous products as a carburizing agent for the briquette, but may use fish or vegetable oils also. These oils are allmuch less stable than petroleum oil, breaking up into fixed gases, solid and semi-solid substances at temperatures far below those necessary to decompose petroleum. As a vehicle for the briquette I may use any solid substance, but prefer to use some substance which will decompose into desirable products. I find that sawdust is very good for thisuse, sinceit decomposes into pyroligneous prod nets and assists rather than interferes with the cementat-ion in the carburizing chamber.

I claim as my invention:

1. A carburizing apparatus comprising: walls forming a carburizing chamber; means for heating said carburizing chamber; a comparatively long drop tube connected with said carburizing chamber; walls forming a briquette chamber, said briquette chamber being adapted to have communication with said carburizing chamber by means of said drop tube; and means for separating said briquette chamber from said carburizing cham ber.

2. A carburizing apparatus comprising: Walls forming a carburizing chamber; means for heating said carburizing chamber; a comparatively long drop tube extending upward from said carburizing chamber; Walls forming a briquette chamber at the remote end of said tube; and a gate for closing the end of said carburizing chamber adjacent to the remote end of said tube.

3. A carburizing apparatus comprising: Walls forming a carburizing chamber; means for heating said carburizing chamber; a comparatively long drop tube extending upward from said carburizing chamber; walls forming a briquette chamber at the remote end of said tube; and a gate for closing the end of saidcarburizing chamber adjacent to the re mote end of said tube, said gate being movable to connect said briquette chamber With said tube.

In testimony whereof I have hereunto setmy hand at Los Angeles, California this 16th day of October, 1925.

PETER CHAMBERS. 

